In the following patent document 1, there is described a tire for heavy loads, wherein a sidewall rubber of a double structure is disposed in a sidewall portion. The sidewall rubber includes an inside rubber which is disposed in an inner side in the tire axial direction and whose loss tangent and complex elastic modulus are small, and an outside rubber which is disposed outside the inside rubber and whose loss tangent and complex elastic modulus are large.
In such tire for heavy loads, owing to the inside rubber, the energy loss in an inside part of the sidewall portion, where flexure is large during running, is decreased. Consequently, the rolling resistance performance becomes small.
Further, owing to the outside rubber, the weatherproof and resistance to external damage of an outside part of the sidewall portion can be prevented from deteriorating, and the durability performance is improved.
However, tires for heavy loads like this are required to be further improved in the rolling resistance performance and durability performance, responding to recent global environmental issues.